How to create a useful MySQL bug report

...and make sure it is properly processed

Valerii Kravchuk, Principal Support Engineer, MariaDBvkravchuk@gmail.com

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Who am I and why this is about MySQL bugs?

Valerii (aka Valeriy) Kravchuk:● MySQL Support Engineer (bugs verification team) in MySQL AB, Sun and

Oracle, 2005 - 2012● Principal Support Engineer in Percona, 2012 - 2016● Principal Support Engineer in MariaDB Corporation since March 2016● http://mysqlentomologist.blogspot.com - my blog about MySQL (a lot about

MySQL bugs, but some HowTos as well)● https://www.facebook.com/valerii.kravchuk - my Facebook page, a lot about

MySQL (mostly bugs, rants and links to blog posts…)● http://bugs.mysql.com - it used to be my personal playground● @mysqlbugs - #bugoftheday on Twitter● I like FOSDEM, see slides from my previous talks:

○ http://www.slideshare.net/valeriikravchuk1/fosdem2015-gdb-tips-and-tricks-for-my-sql-db-as○ http://www.slideshare.net/ValeriyKravchuk/more-on-gdb-for-my-sql-db-as-fosdem-2016○ https://www.slideshare.net/ValeriyKravchuk/applying-profilers-to-my-sql-fosdem-2017

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Topics to discuss

● Why should we report bugs at https://bugs.mysql.com (or other public tracker)?

● What is a “Useful MySQL Bug Report”?● What to do before reporting a bug?● How to search for known MySQL bugs efficiently?● What tools may help to create a useful bug report?● Life cycle of Oracle/MySQL public bug report● Life cycle of MariaDB JIRA bug report● Examples of useful bug reports● Examples of useless bug reports● How to escalate bug reports?

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Always report bugs in public!

● Why? I am customer!○ I tried to explain in a separate blog post○ Public bug reports are easy to search for: site:bugs.mysql.com drop

add index InnoDB○ Public bug reports becomes visible to other customers, community

members and MySQL support providers and developers outside of Oracle

● Public bug trackers: ○ https://bugs.mysql.com - MySQL software from Oracle○ https://jira.mariadb.org/browse/MDEV - MariaDB Server○ https://jira.percona.com/browse/PS - Percona Server

● What about security bugs?○ Do NOT report bug as a “security” one unless it is really that serious

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Features of a useful bug report

● It’s a real, new bug that was never reported before (or was once fixed but now appeared again, “regression”)

● It’s clear what the bug is and how to reproduce it● Bug reporter cared to check on the latest officially released

version in the branch (?) What if it’s on a custom build from GitHub source code?

● All important details about the environment and impact are provided

● It’s clear that bug reporter spent enough efforts on it (search, testing, minimal test case) (?)

● Anything wrong or missed in the above? (use proper tags)

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Before reporting a bug...

● Try to find similar already reported bugs● Try to find a solution/reason by reading the manual● Try to reproduce the bug in a “clean environment”● Make sure you’ve read vendor-specific (and product

specific, if any) instructions:○ https://mariadb.com/kb/en/mariadb/development/debugging-mariadb/report

ing-bugs/ ○ https://bugs.mysql.com/how-to-report.php○ http://mysqlworkbench.org/faq/faq-bugreporting/

● Make sure you’ve read this entirely at least once:http://www.catb.org/esr/faqs/smart-questions.html

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How to search for known bugs?

● Use Google like this:site:bugs.mysql.com drop table slowand check at least first 3 pages of results and links there

● Search for specific error messages, lines from stack trace, versions, filenames and line numbers, names

● Do not ignore bug tracker specific search:○ Specific categories○ Bugs vs. Feature requests○ Specific version, bug status, q etc

● Study features and limitations of your search tools● Keep your own notes and test cases “database”

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Tools for bug reporters (and QA engineers)● MySQL Sandbox (dbdeployer), Docker, VMs● MTR (MySQL regression test suite)● OS tools: gdb, strace, lsof, perf... ● Percona Toolkit (pt-summary, pt-mysql-summary, pt-pmp)● sysbench in case of performance problems● Debug binaries and trace● Valgrind and Massif:

○ http://www.percona.com/blog/2013/01/09/profiling-mysql-memory-usage-with-valgrind-massif/

● Randgen (RQG)○ http://www.percona.com/blog/2014/04/17/how-to-find-bugs-in-mysql/

● Percona QA tools:○ http://www.percona.com/blog/2014/09/03/reducer-sh-a-powerful-mysql-test-case-simplificationre

ducer-tool/

● Anything else?8

Life cycle of a MySQL bughttp://mysqlentomologist.blogspot.com/2013/01/life-cycle-of-mysql-bug.html

● Open● Analyzing (usually assigned)● Need Feedback → No Feedback (expires in 30 days)● Can’t repeat● Verified → copied to internal database → Closed one day● Not a Bug● Duplicate● Unsupported● Won’t fix● In progress… (real progress happens elsewhere)● Closed ← when fixed in internal database, before release● What about feature requests?

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Life cycle of a MariaDB (Server) bug (JIRA issue)http://mysqlentomologist.blogspot.com/2018/12/mariadb-jira-for-mysql-dbas.html

● OPEN - may be assigned, may need feedback● CONFIRMED - usually also assigned● STALLED - some work on it was performed● IN PROGRESS - assignee is currently working on the fix for the bug.● IN REVIEW - assignee is currently reviewing the fix for the bug.● CLOSED - the bug is resolved somehow. "Resolution":

○ Fixed○ Duplicate○ Won’t Fix○ Cannot reproduce○ Incomplete○ Not a Bug

● See also a table that matches MySQL “Status” with MariaDB “Status” + “Resolution” + “Labels” here

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Examples of useful bug reports● Bug #93963 - steps to create big enough table are missed, but otherwise it’s

clear and important detail (regression vs 5.7) is highlighted● Bug #93957 - refers to older bug (with proper public test case) that was

closed/fixed, but seems to re-appear in 5.7.24.● Bug #91941 - gdb backtrace from production, collective efforts

● Bug #69979 - test case, how repeatable read works (NaB, but useful reading!)● Bug #73837 - how to report optimizer bugs● Bug #68705 - Valgrind in use. Still just “Verified”.● Bug #73825 - simple wrong results bug. Still just “Verified”.● Bug #73881 - RQG in action. Still just “Verified”.● Bug #68554 - optimizer trace, level of details, how ICP works● Bug #69253 - with patch suggested (mind OCA)● Bug #73018 - even perfect reports with a patch and OCA signed may stay

Open or Verified for years

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Examples of useless bug reports

● Bug #55796 - “it really sucks”, gotcha… Read the manual, ask for a feature...

● Bug #73960 - “this query is very slow”, no facts, no feedback

● Bug #73921 - free support request, no feedback eventually● Bug #73844 - near zero information, no feedback

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How to escalate the bug?

Verified (or Open but real) bug is not fixed. What to do?

● Cooperate, try to provide feedback when requested● Comment, ask, curse, complain in report● Ask others to comment, use “Affects Me” button or similar● Report it again? Only if closed bug is still repeatable ● Report it in other bug tracker (to other company)● Ask some developer in private● Blog about it● Open issue (support request) about it● Complain in social media● Tell me (or somebody who cares) about it

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They process your bug reports!

● Umesh Shastry (Oracle, 50+% of all bugs Verified)● Shane Bester (MySQL, Sun, Oracle)● Miguel Solorzano (MySQL, Sun, Oracle)● Elena Stepanova (Sun, Oracle, MariaDB)● Sveta Smirnova (MySQL, Sun, Oracle, Percona)● Laurynas Biveinis (Percona)● Roel Van de Paar (MySQL, Sun, Oracle, Percona)

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Any specific bug reports you want to discuss?

● Find me somewhere around today● Ask me at Facebook or Twitter● That’s what I’d like to discuss today:

“Private” and “Security” bugs in public bugs databases. Should they exist, who decides on these statuses, when they should become public (including test cases)?

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Thank you!Questions and Answers?

Please, report bugs at:

https://bugs.mysql.com

https://jira.mariadb.org

https://jira.percona.com

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